Keyboard is an important device for communication between people and technology, and commonly used as a communication interface with computers or other digital devices. With progress of technology, different types of linkage have been developed to the keyboard.
Initially linkage between the keyboard and computer adopted a communication interface standard of RS-232/DB-9, then advanced to PS/2 communication interface, and finally has progressed to USB communication interface now with greatest compatibility, which adopts wired connection. However, as applications of computers and digital devices have gradually personalized and entered into people's daily life, application environments are no longer limited to office desks or computer tables. Naturally linkage between the keyboard and computers or digital devices also evolves from the wired connection within a limited distance to wireless connection within a wider area.
To meet wireless transmission requirement on the keyboard, infrared transmission technique was first widely adopted. However, infrared transmission is directional and a smooth high speed connection of the infrared transmission often is limited to a short distance within few meters and obstacles therebetween. Hence these cause strict limitations on use angles and distance of the wireless keyboard. As a result, infrared-enabled keyboard is not well received by most users and has gradually faded out from the market.
In recent years, plenty of electronic industries have set up a common wireless communication standard of Bluetooth communication technology. It not only increases the linking distance, but also overcomes use angle problem and provides greater compatibility. Aside from being adopted on mobile communication field, it also has been expanded to keyboard, mouse and game machine fields.
However, take the Bluetooth keyboard to be used as an input device, the system (such as computer or mobile phone) receiving Bluetooth keyboard signals must have a Bluetooth transmission module to establish a linkage with the Bluetooth keyboard. But the Bluetooth transmission module is not yet a built-in device in the general computer. Hence even if a user carries a Bluetooth keyboard, it does not mean the Bluetooth keyboard can establish a linkage with any devices whenever desired. This causes use limitation.